1. Field of the Invention
The present invention relates to an electroconductive member and an electrophotographic apparatus. More particularly, it pertains to an electroconductive member imparted with an antistatic function such as a packaging member or a shock-absorbing member, or a developing member and image transfer member that are employed in an electrophotographic mechanism, and to an electrophotographic apparatus using said electroconductive member.
2. Description of the Related Arts
With the advance of electronic technique, eager and increasing demands have recently been imposed on an electroconductive member in which an antistatic function is required for the purpose of protecting electronic part items and which is exemplified by a packaging member, a shockabsorbing member and members utilized in an electrophotographic apparatus such as a laser printer and a dry type copying machine. Among the electroconductive members, intensive attention has been paid to an elastic roller having an intermediate electric-resistance to be used in such a process as development and image transfer.
The electroconductive member to be used for such a purpose of use has heretofore been prepared from a high molecular material (including the foam therefrom) such as rubber and polyurethane that are regulated to a prescribed electric-resistance by mixing therein a powder or whisker of a metal or a metal oxide and/or a filler such as carbon black. The performance required for the above-mentioned electroconductive member include not only a prescribed electric-resistance of 1.times.10.sup.4 to 1.times.10.sup.12 .OMEGA. in the intermediate resistance region but also less variation range in the electric resistance between the circumstances of low temperature and low humidity and those of high temperature and high humidity.
However, the problems still remain unsolved in that it is difficult to regulate the electric resistance of an electroconductive member at a constant level by mixing therein carbon black or the like and also that the electroconductive member comprising a high molecular material regulated to a prescribed electric-resistance by mixing therein a powder or whisker of a metal or a metal oxide and/or a filler such as carbon black, suffers great positional dispersion of electric resistance as well as remarkable dependence of electric resistance upon voltage.
In such circumstances, there is produced an electroconductive member which is substantially freed from dispersion in electric resistance or dependence thereof on voltage in the intermediate resistance region by mixing therein an tonically electroconductive substance such as sodium perchlorate.
Nevertheless, a roller made of such an electroconductive member involves the problems of much variation range in the electric resistance between the circumstances of high temperature and high humidity such as 32.5.degree. C./85% R.H. and those of low temperature and low humidity such as 15.degree. C./10% R.H.; gradual increase in its electric resistance with continuous running under the condition of electric current passage; and the occurrence of poor image in the case of the roller being used for electrophotography.